Studies of the "activitystat" hypothesis

This dissertation explored the potential existence of an "activitystat:" a biologically controlled regulatory mechanism for physical activity. This was accomplished through two studies of participants in the Trial of Activity for Adolescent Girls (TAAG). The first study examined the tracking of physical activity over a two-year time period. In the second study we investigated the associations between physical activity and inactivity. It has been suggested that tracking, or stability, of physical activity levels over time is indication that an "activitystat" exists. That is, despite changes in social and environmental influences on physical activity over time, an individual's relative rank of physical activity within a group remains consistent. TAAG provided a unique opportunity to examine tracking since it included both an objective and subjective measure of inactivity and physical activity. In 951 participants who were measured in 6th grade and two years later in 8th grade, tracking of inactivity, moderate-to-vigorous physical activity, and vigorous physical activity was fair-to-moderate. Objectively measured tracking tended to be higher than that from self-reported inactivity and physical activity. These results cast some doubt on the "activitystat" hypothesis as they suggest that physical activity and inactivity habits are dynamic for most girls during early adolescence. The "activitystat" hypothesis also posits that increases in moderate-to-vigorous physical activity are accompanied by a compensatory reduction in light physical activity and an increase in inactivity in order to maintain a consistent total physical activity level from day to day. In 6,916 8th grade TAAG participants we found no associations over 6 days of measurement between physical activity and inactivity that would suggest compensatory changes occur that would result in the maintenance of total physical activity levels. As girls increased their inactivity total physical activity decreased, as moderate-to-vigorous physical activity increased inactivity decreased, and as moderate-to-vigorous physical activity increased light physical activity increased. This dissertation failed to find support for the "activitystat" hypothesis. These findings may indicate that well-designed physical activity interventions for adolescent girls should be able to produce positive results through either increasing physical activity or decreasing inactivity

Association between physical activity and risk of stroke subtypes: The Atherosclerosis Risk in Communities (ARIC) Study

The relationship between stroke subtypes and physical activity is unclear

The 1.6 micron near infrared nuclei of 3C radio galaxies: Jets, thermal emission or scattered light?

Using HST NICMOS 2 observations we have measured 1.6-micron near infrared nuclear luminosities of 100 3CR radio galaxies with z<0.3, by modeling and subtracting the extended emission from the host galaxy. We performed a multi-wavelength statistical analysis (including optical and radio data) of the properties of the nuclei following classification of the objects into FRI and FRII, and LIG (low-ionization galaxies), HIG (high-ionization galaxies) and BLO (broad-lined objects) using the radio morphology and optical spectra, respectively. The correlations among near infrared, optical, and radio nuclear luminosity support the idea that the near infrared nuclear emission of FRIs has a non-thermal origin. Despite the difference in radio morphology, the multi-wavelength properties of FRII LIG nuclei are statistically indistinguishable from those of FRIs, an indication of a common structure of the central engine. All BLOs show an unresolved near infrared nucleus and a large near infrared excess with respect to FRII LIGs and FRIs of equal radio core luminosity. This requires the presence of an additional (and dominant) component other than the non-thermal light. Considering the shape of their spectral energy distribution, we ascribe the origin of their near infrared light to hot circumnuclear dust. A near infrared excess is also found in HIGs, but their nuclei are substantially fainter than those of BLO. This result indicates that substantial obscuration along the line-of-sight to the nuclei is still present at 1.6 micron. Nonetheless, HIGs nuclei cannot simply be explained in terms of dust obscuration: a significant contribution from light reflected in a circumnuclear scattering region is needed to account for their multiwavelength properties.Comment: 20 pages, 16 figures. Accepted for publication on Ap

The population burden of heart failure attributable to modifiable risk factors: The ARIC (atherosclerosis risk in communities) study

OBJECTIVES: The goal of this study was to estimate the population burden of heart failure and the influence of modifiable risk factors. BACKGROUND: Heart failure is a common, costly, and fatal disorder, yet few studies have evaluated the population-level influence of modifiable risk factors. METHODS: From 14,709 ARIC (Atherosclerosis Risk in Communities) study participants, we estimated incidence rate differences (IRD) for the association between 5 modifiable risk factors (cigarette smoking, diabetes, elevated low-density lipoproteins, hypertension, and obesity) and heart failure. Potential impact fractions were used to measure expected changes in the heart failure incidence assuming achievement of a 5% proportional decrement in the prevalence of each risk factor. RESULTS: Over an average of 17.6 years of follow-up, 1 in 3 African American and 1 in 4 Caucasian participants were hospitalized with heart failure, defined as the first hospitalization with International Classification of Diseases, Ninth Revision discharge codes of 428.x. Of the 5 modifiable risk factors, the largest IRD was observed for diabetes, which was associated with 1,058 (95% confidence interval [CI]: 787 to 1,329) and 660 (95% CI: 514 to 805) incident hospitalizations of heart failure/100,000 person-years among African-American and Caucasian participants, respectively. A 5% proportional reduction in the prevalence of diabetes would result in approximately 53 and 33 fewer incident heart failure hospitalizations per 100,000 person-years in African-American and Caucasian ARIC participants, respectively. When applied to U.S. populations, this reduction may prevent approximately 30,000 incident cases of heart failure annually. CONCLUSIONS: Modest decrements in the prevalence of modifiable heart failure risk factors such as diabetes may substantially decrease the incidence of this major disease

Temporal Trends in Medical Therapies for ST- and Non-ST Elevation Myocardial Infarction: (from the Atherosclerosis Risk in Communities [ARIC] Surveillance Study)

Reports from large studies using administrative datasets and event registries have characterized recent temporal trends and treatment patterns for AMI. However, few are population-based and fewer have examined differences in patterns of treatment for patients presenting with ST elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI). We examined 22-year trends in the use of 10 medical therapies and procedures by STEMI and NSTEMI classification in 30986 definite or probable MIs in the ARIC Community Surveillance Study from 1987 to 2008. We used weighted multivariable Poisson regression controlling for sex, race/center classification, age, and PREDICT score to estimate average annual percent changes in medical therapy use. From 1987 – 2008, 6106 (19.7%) hospitalized events were classified as STEMI, and 20302 (65.5%) were classified as NSTEMI. Among STEMI patients, increases (%; 95% CI) were noted in the use of ACE inhibitors (6.4; 5.7, 7.2), non-aspirin anti-platelets (5.0; 4.0, 6.0), lipid-lowering medications (4.5; 3.1, 5.8), beta blockers (2.7; 2.4, 3.0), aspirin (1.2; 1.0, 1.3), and heparin (0.8; 0.4, 1.3). Among NSTEMI patients, the use of ACE inhibitors (5.5; 5.0, 6.1), non-aspirin anti-platelets (3.7; 2.7, 4.7), lipid-lowering medications (3.0; 1.9, 4.1), beta blockers (4.2; 3.9, 4.4), aspirin (1.9, 1.6; 2.1), and heparin (1.7; 1.3, 2.1) increased. Among STEMI patients, we observed decreases in the use of thrombolytics (-7.2; -7.9, -6.6) and CABG (-2.4%; -3.6, -1.2). We noted similar increases in PCI and decreases in the use of thrombolytics and CABG among all patients. In conclusion, we found trends of increasing use of evidence-based therapies for both STEMI and NSTEMI patients over the past 22 years

Do Overweight Girls Overreport Physical Activity?

To determine if overweight adolescent girls are more likely to overreport physical activity compared to normal-weight girls

Oral steroids for the resolution of otitis media with effusion (OME) in children (OSTRICH): study protocol for a randomised controlled trial

Background Otitis media with effusion (OME) is an accumulation of fluid in the middle ear affecting about 80% of children by the age of 4 years. While OME usually resolves spontaneously, it can affect speech, behaviour and development. Children with persistent hearing loss associated with OME are usually offered hearing aids or insertion of ventilation tubes through the tympanic membrane. Oral steroids may be a safe and effective treatment for OME, which could be delivered in primary care. It has the potential to benefit large numbers of children and reduce the burden of care on them and on health services. However, previous trials have either been too small with too short a follow up period, or of too poor quality to give a definite answer. The aim of the OSTRICH trial is to determine if a short course of oral steroids improves the hearing of children with OME in the short and longer term. Methods/Design 380 participants (children aged 2-8 years) are recruited from Hospital Ear, Nose and Throat departments in Wales and England. A trained clinician seeks informed consent from parents of children with symptoms attributable to OME for at least 3 months and with confirmed bilateral hearing loss at study entry. Participants are randomised to a course of oral steroid or a matched placebo for one week. Outcomes include audiometry, tympanometry and otoscopy assessments, symptoms, adverse effects, functional health status, quality of life, resource use and cost effectiveness. Participants are followed up at 5 weeks, and at 6 and 12 months after the day of randomisation. The primary outcome is audiometry-confirmed satisfactory hearing at 5 weeks. Discussion There is an important evidence gap regarding clinical and cost effectiveness of short courses of oral steroid treatment for OME. Identifying an effective, safe, non-surgical intervention for OME in children for use in primary care would be of great benefit to children, their families and the NHS

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Digital auscultation in PERCH: Associations with chest radiography and pneumonia mortality in children.

BACKGROUND: Whether digitally recorded lung sounds are associated with radiographic pneumonia or clinical outcomes among children in low-income and middle-income countries is unknown. We sought to address these knowledge gaps. METHODS: We enrolled 1 to 59monthold children hospitalized with pneumonia at eight African and Asian Pneumonia Etiology Research for Child Health sites in six countries, recorded digital stethoscope lung sounds, obtained chest radiographs, and collected clinical outcomes. Recordings were processed and classified into binary categories positive or negative for adventitial lung sounds. Listening and reading panels classified recordings and radiographs. Recording classification associations with chest radiographs with World Health Organization (WHO)-defined primary endpoint pneumonia (radiographic pneumonia) or mortality were evaluated. We also examined case fatality among risk strata. RESULTS: Among children without WHO danger signs, wheezing (without crackles) had a lower adjusted odds ratio (aOR) for radiographic pneumonia (0.35, 95% confidence interval (CI): 0.15, 0.82), compared to children with normal recordings. Neither crackle only (no wheeze) (aOR: 2.13, 95% CI: 0.91, 4.96) or any wheeze (with or without crackle) (aOR: 0.63, 95% CI: 0.34, 1.15) were associated with radiographic pneumonia. Among children with WHO danger signs no lung recording classification was independently associated with radiographic pneumonia, although trends toward greater odds of radiographic pneumonia were observed among children classified with crackle only (no wheeze) or any wheeze (with or without crackle). Among children without WHO danger signs, those with recorded wheezing had a lower case fatality than those without wheezing (3.8% vs. 9.1%, p = .03). CONCLUSIONS: Among lower risk children without WHO danger signs digitally recorded wheezing is associated with a lower odds for radiographic pneumonia and with lower mortality. Although further research is needed, these data indicate that with further development digital auscultation may eventually contribute to child pneumonia care

Current and emerging developments in subseasonal to decadal prediction

Weather and climate variations of subseasonal to decadal timescales can have enormous social, economic and environmental impacts, making skillful predictions on these timescales a valuable tool for decision makers. As such, there is a growing interest in the scientific, operational and applications communities in developing forecasts to improve our foreknowledge of extreme events. On subseasonal to seasonal (S2S) timescales, these include high-impact meteorological events such as tropical cyclones, extratropical storms, floods, droughts, and heat and cold waves. On seasonal to decadal (S2D) timescales, while the focus remains broadly similar (e.g., on precipitation, surface and upper ocean temperatures and their effects on the probabilities of high-impact meteorological events), understanding the roles of internal and externally-forced variability such as anthropogenic warming in forecasts also becomes important. The S2S and S2D communities share common scientific and technical challenges. These include forecast initialization and ensemble generation; initialization shock and drift; understanding the onset of model systematic errors; bias correct, calibration and forecast quality assessment; model resolution; atmosphere-ocean coupling; sources and expectations for predictability; and linking research, operational forecasting, and end user needs. In September 2018 a coordinated pair of international conferences, framed by the above challenges, was organized jointly by the World Climate Research Programme (WCRP) and the World Weather Research Prograame (WWRP). These conferences surveyed the state of S2S and S2D prediction, ongoing research, and future needs, providing an ideal basis for synthesizing current and emerging developments in these areas that promise to enhance future operational services. This article provides such a synthesis